Rotor locks systems are needed on wind turbines in order to assure that the rotor is not rotating when service activities takes place. The lock is usually part of the redundant system which also includes the brake.
Typically the rotor lock system comprises one or more pins (often two pins) which are pushed into holes in the hub, the main shaft or a loose flange. The pins are attached to the non moving part of the wind turbine and thereby preventing a rotation of the drive train.
As wind turbines are becoming bigger the dimensions are also increased. This increase in dimensions leads to increased absolute tolerances in the relative position of the pins and the locking holes. Additionally the structural deflections due to the large weight of the drive train may lead to further problems in the alignment of the pins and holes.
These problems in aligning the pins and the holes leads to an uneven load sharing between the pins due to the torque. A consequence of this is that the main bearings of the drive train will be subjected to loads originating from the torque. In the extreme case only one of the pins may react to the torque load and thus the main shaft will become loaded with a force equivalent of the pin reaction force. The force on the shaft is counteracted by the main bearing(s) and hence the bearings may be subjected to relative high loads in a standstill configuration.
The loading of bearings in a standstill configuration is usually undesirable due to the risk of false brinelling and the risk of metal to metal contacts when the lubricant has been pushed out of the contact zone.
EP 1 291 521 A1 discloses a rotor lock system using pins with tapered ends and holes with tapered apertures allowing for compensation of misalignment between the pins and the holes and the elimination or at least reduction of the play between the pins and the holes.
However this system does not solve all alignment problems involved in big turbines. This invention is intended to solve this drawback.